They now do Laser Engraving of Diamonds they have a number and other
things engraved on the edge not visible with the eye. What I saw was
very very good below is what I found with a search on Google.
The laser can inscribe incredibly small characters; even down to one
tenth the thickness of a human hair, so a significant inscription
can be inscribed on the diamond and remain invisible to the naked
eye until viewed under a 10x magnifying glass (which we can also
Laser Engraving of Diamonds
A ‘diamond is forever’ and now your very own personal message of
Love can also be forever. A testament to your love, more enduring
than the Pyramids, to be passed on down through the generations.
With our unique micro-laser engraving service you can now engrave a
diamond with the inscription of your choice. It could be a personal
message, wedding date, birth date, a security identification number,
diamond certificate details, zip or post code or even a company
logo. You may also select from a range of Standard messages.